I am looking for a long lens to mount via an adapter on my Contax 645 MFDB system to photograph wildlife and am having a hard time deciding which is "best" given that price for a preloved 400mm Pentax 67 SMC Takumar f4 & 350mm Hasselblad C f5.6? is about the same.

Is the optics & coating of the Hasselblad 350mm lens superior to the Pentax lens 400mm?

What difference does weight and size of these two lenses make when photographing from a heavy duty car window mount like the Kirk WM2?

Is the 1-stop advantage of the Pentax (f4 compared to f5.6) and the fact that the coverage of the Pentax is 67 likely to make much difference?

It has been at least 12 years since I last shot with a Pentax 67 system but when I shot with both a P'67 and a Hasselblad in the late '90s the Super Takumars were every bit as good as and sometimes better than the Zeiss CF lenses.

I am looking for a long lens to mount via an adapter on my Contax 645 MFDB system to photograph wildlife and am having a hard time deciding which is "best" given that price for a preloved 400mm Pentax 67 SMC Takumar f4 & 350mm Hasselblad C f5.6? is about the same.

Is the optics & coating of the Hasselblad 350mm lens superior to the Pentax lens 400mm?

What difference does weight and size of these two lenses make when photographing from a heavy duty car window mount like the Kirk WM2?

Is the 1-stop advantage of the Pentax (f4 compared to f5.6) and the fact that the coverage of the Pentax is 67 likely to make much difference?

Ignoring for a moment the spurious consideration of convenience (ie what is humanly doable without hiring Lance Armstrong as a consultant), would not the synchro-compur shutter in the 350mm Hassy C lens be more helpful than the in-body focal plane shutters most other lenses in this class rely on when it comes to combatting the risk of camera shake that can ruin a lot of otherwise superb shots when working with old bazookas like these, even on a tripod?

Ignoring for a moment the spurious consideration of convenience (ie what is humanly doable without hiring Lance Armstrong as a consultant), would not the synchro-compur shutter in the 350mm Hassy C lens be more helpful than the in-body focal plane shutters most other lenses in this class rely on when it comes to combatting the risk of camera shake that can ruin a lot of otherwise superb shots when working with old bazookas like these, even on a tripod?

Or a lens support something like this Manfrotto 293 telephoto lens support that is a clever concept but according to the specs can only handle a max weight of 2.5kg that is not enough. Alternative suggestions for telephoto lens support systems welcome particularly if it does not cost more than the camera?